Electromagnetic wave attenuation film and manufacturing method of same

Abstract

A electromagnetic wave attenuation film includes a substrate provided with a dielectric substrate having a front surface and a back surface, and thin film conductive layers arranged on both the front surface and the back surface of the electromagnetic wave attenuation substrate; a support layer arranged on the back surface of the electromagnetic wave attenuation substrate; and a flat plate inductor arranged on the back surface of the support layer; wherein the thin film conductive layers include a plurality of conductive elements. Furthermore, the conductive elements are arranged periodically, and when a distance in a plane direction between a center of gravity of the conductive elements on the front surface and the back surface is 1, and a shortest distance from the center of gravity of the conductive elements to a plate end portion is a, equation (1) below may be satisfied. I≤5.2a . . . (1)

What is claimed is: 
     
         1 . An electromagnetic wave attenuation film, comprising:
 an electromagnetic wave attenuation substrate provided with a dielectric substrate having a front surface and a back surface, and thin film conductive layers arranged on both the front surface and the back surface of the electromagnetic wave attenuation substrate;   a support layer arranged on the back surface of the electromagnetic wave attenuation substrate; and   a flat plate inductor arranged on a back surface of the support layer; wherein   the thin film conductive layers include a plurality of conductive elements.   
     
     
         2 . The electromagnetic wave attenuation film of  claim 1 , wherein
 the conductive elements are arranged periodically, and   when a distance in a plane direction between a center of gravity of the conductive elements on the front surface and the back surface of the dielectric substrate is 1, and a shortest distance from the center of gravity of the conductive elements to a plate end portion is a, equation (1) below is satisfied.   
       
         
           
             
               
                 
                   
                     I 
                     ≦ 
                     
                       5.2 
                       a 
                     
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
       
     
     
         3 . The electromagnetic wave attenuation film of  claim 1 , wherein
 the conductive elements are arranged periodically, and   when a thickness of the conductive elements is T, and a skin depth is d, equation (4) below is satisfied.   
       
         
           
             
               
                 
                   
                     
                       - 
                       2 
                     
                     ≦ 
                     
                       ln 
                       ⁡ 
                       ( 
                       
                         T 
                         / 
                         d 
                       
                       ) 
                     
                     ≦ 
                     1 
                   
                 
                 
                   
                     ( 
                     4 
                     ) 
                   
                 
               
             
           
         
       
     
     
         4 . The electromagnetic wave attenuation film of  claim 1 , wherein
 the conductive elements are arranged periodically, and   when a distance in a plane direction between a center of gravity of the conductive elements on the front surface and the back surface of the dielectric substrate is 1, and a shortest distance from the center of gravity of the conductive elements to a plate end portion is a, electromagnetic wave attenuation performance is exhibited at multiple frequencies as a result of mixing a combination of conductive elements on the front surface and the back surface of the dielectric substrate satisfying equation (6) below, and a combination of conductive elements on the front surface and the back surface of the dielectric substrate satisfying equation (7) below.   
       
         
           
             
               
                 
                   
                     I 
                     < 
                     
                       2 
                       ⁢ 
                       a 
                     
                   
                 
                 
                   
                     ( 
                     6 
                     ) 
                   
                 
               
             
           
         
         
           
             
               
                 
                   
                     I 
                     ≧ 
                     
                       2 
                       ⁢ 
                       a 
                     
                   
                 
                 
                   
                     ( 
                     7 
                     ) 
                   
                 
               
             
           
         
       
     
     
         5 . The electromagnetic wave attenuation film of  claim 1 , wherein
 a front surface and a back surface of the thin film conductive layer on the front surface of the dielectric substrate is provided with a blackening layer.   
     
     
         6 . The electromagnetic wave attenuation film of  claim 1 , wherein
 a front surface and a back surface of the thin film conductive layer on the back surface of the dielectric substrate is provided with a blackening layer.   
     
     
         7 . The electromagnetic wave attenuation film of  claim 1 , wherein
 the thin film conductive layers are capable of capturing an electromagnetic wave incident from a front surface side of the dielectric substrate.   
     
     
         8 . The electromagnetic wave attenuation film of  claim 1 , wherein
 the conductive elements are planar elements and have a pair of opposing sides.   
     
     
         9 . The electromagnetic wave attenuation film of  claim 1 , wherein
 a thickness of the dielectric substrates is less than one-tenth of an attenuation center wavelength.   
     
     
         10 . The electromagnetic wave attenuation film of  claim 2 , wherein
 a size of the conductive elements on the front surface of the dielectric substrate is smaller than a size of the conductive elements on the back surface of the dielectric substrate and have absorption peak frequencies that are different from each other.   
     
     
         11 . The electromagnetic wave attenuation film of  claim 10 , wherein
 an absorption peak frequency ratio between the absorption peak frequencies that are different from each other is 1.153 or more.   
     
     
         12 . A manufacturing method of an electromagnetic wave attenuation film, comprising the steps of:
 a step for performing simultaneous front and back formation of a predetermined repeating pattern formed of a plurality of conductive elements on a front surface of a dielectric substrate (hereinafter referred to as “front surface pattern”), and a predetermined repeating pattern formed of a plurality of conductive elements on a back surface of the dielectric substrate (hereinafter referred to as “back surface pattern”);   a step for laminating a support layer on the back surface of the dielectric substrate on which patterns have been formed on the front and back; and   a step for forming a flat plate inductor on a back surface of the support layer.   
     
     
         13 . The manufacturing method of an electromagnetic wave attenuation film of  claim 12 , further comprising
 a step for attaching, to the back surface of the dielectric substrate on which the front surface pattern and the back surface pattern have been formed, a front surface of the support layer on which the flat plate inductor has been formed.   
     
     
         14 . The manufacturing method of an electromagnetic wave attenuation film of  claim 12 , wherein
 a shape and/or a position of the front surface pattern and the back surface pattern are different from each other.   
     
     
         15 . The manufacturing method of an electromagnetic wave attenuation film of  claim 12 , wherein
 the front surface pattern and the back surface pattern are formed by a photolithography method.